Rump Shaker
by LadyDivine91
Summary: Kurt suspects something's been going on between his husband and Mercedes. Ever since they found out that the IVF worked and Mercedes was carrying Blaine's baby, the two of them have gotten closer. If Kurt hadn't come home from work early, he would have never discovered the truth … Klaine. Kurt H. Blaine A.


**Dedicated to mypopculturesummer for commenting on the post I reblogged - post/157951589587/k-nowitallchronicles-start-putting-mercedes-in - and added to xD Also based off of a video I saw on Facebook. I can't link it, but you'll get the gist 3**

Kurt would have never found out if he didn't come home early.

When he comes home on time, around eight in the evening, it's usually to Mercedes sitting on the sofa in front of the TV while Blaine makes dinner in the kitchen. It's an interesting arrangement, having them all living together. Mercedes and Blaine had always been fond of one another, but they'd never been what you'd call _friends_. But as time went on, Blaine and Mercedes became closer. They watched TV together when Kurt wasn't home, talked about music and fashion, read the same magazines.

His best friend and his husband spending more time together than either of them spend with him? Kurt was beginning to feel jealous.

He began to think that something was going on between them, something more than TV shows and magazines, but he forced himself not to see it.

But now, as he stands outside the loft door, key in hand, he can hear them – the rhythmic banging, heavy breathing, coy giggling, and loud, Latin music that doesn't quite cover up their betrayal.

Kurt had his suspicions – the way Blaine adverts his eyes when Kurt comes home, Mercedes's flushed face. They'd always have an excuse, but nothing that held water. Still, it didn't add up … until now.

Kurt trusted them, dammit! He knew they'd been getting closer after Blaine started working from home, but he never expected this! Them sneaking around behind his back!

Why couldn't they be upfront with him? Why couldn't they just tell him?

Why would they leave him out?

It's the pregnancy. Ever since they found out that the IVF worked and she was pregnant with _Blaine's_ baby, she'd been able to convince Kurt's husband to do anything she wanted – late night snack runs, back rubs, mani-pedis.

But this was going too far. Keeping secrets! Kurt abhors keeping secrets!

Kurt has to catch them in the act. He has to peel this off like a Band-Aid and expose them once and for all. He's going to shove the door open, and he's going to end this once and for all. He ignores the knots in his stomach and counts to three in his head.

 _One_ ….

He puts the key in the lock.

 _Two_ …

He turns it till the tumblers click.

 _Three_!

Kurt shoves the door open. There in the living room, not fifteen feet from the door, he sees them - Blaine's chest to Mercedes's back, one hand holding hers above her head, the other wrapped around her swollen tummy, straining the limits of the shameless black lace number she's wearing. They'd even pushed the furniture back to give them more space. God!

Kurt stomps a foot on the floor to break them apart.

It does no good.

"Blaine!" Kurt snaps. "Mercedes!"

Blaine jumps at the sound of Kurt's voice, but Mercedes keeps moving like he's not even there.

"Kurt!" Blaine shoots away from Mercedes's gyrating body, keeping his hands where Kurt can see them. "It-it's not what you think!"

"What do you mean _it's not what I think!_? I'm looking right at the both of you! It's _exactly_ what I think!"

"Don't get so upset, Kurt," Mercedes says, twirling around and shimmying across the floor.

"Of course I'm upset!" Kurt slides the door shut behind him so the neighbors don't hear. "Mercedes! You're my best friend! You're carrying Blaine's and my child!" He storms over to her. "The doctor told you to rest! Remember your blood pressure!"

"I can't be stuck on that sofa all day," Mercedes argues, twirling again. "Tracy Anderson may be half your hubby over there, but she's also half _me_ , and this girl wants to shake it." Mercedes wiggles her rear, backing up against Kurt. Blaine chuckles, but one look from Kurt silences him cold.

Kurt takes a deep breath as Mercedes continues to bump him with her butt, and sighs.

"Okay, okay, okay," Kurt says, shielding his eyes. "Well, I think that's enough _shaking_ for one evening." Kurt switches off Blaine's iPod. Then he puts an arm around Mercedes and helps her to the sofa.

Mercedes waddles along willingly, a little out of breath, but not without a pout. "Party pooper."

"Yeah, well, to be honest, I don't know if I'm more upset at you guys for Salsa dancing behind my back, or …" Kurt stops talking as he lowers Mercedes carefully to her seat.

"Or?" Blaine asks, joining in to help Mercedes sit without plummeting to the couch cushion.

"Or … the fact that you didn't wait for me to get home."


End file.
